改良粉土强度的冻融循环效应与微观机制  

Strength and micromechanism of improved silt under freeze-thaw cycle effect

作　　者：谈云志[1] 吴翩[1] 付伟[2] 万智[3] 张华[1] 张振华[1] 

机构地区：[1]三峡大学 三峡库区地质灾害教育部重点实验室,湖北 宜昌443002 [2]中交第二公路勘察设计研究院有限公司,武汉 430056 [3]湖南省交通科学研究院,长沙 410015

出　　处：《岩土力学》2013年第10期2827-2834,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金项目资助(No.51009084);湖南省交通科技进步与创新计划项目(No.200910,No.201045)

摘　　要：为了研究冻融循环对改良粉土强度的影响规律及其作用机制，开展了不同初始压实度和初始含水率试样的冻融循环试验。对经历不同冻融循环次数作用后的试样进行无侧限抗压强度试验，探讨了冻融循环作用对改良粉土的长期强度的影响规律。试验结果表明，随着冻融循环次数增加，改良粉土的抗压强度下降，最终在6次冻融循环后趋于稳定；相同的冻融循环次数条件下，初始含水率越大，改良粉土的抗压强度衰减幅度越大。为了寻找冻融循环作用对改良粉土孔隙结构的影响规律，进而揭示冻融循环对试样结构损伤的机制，开展了改良粉土的细观孔隙结构试验。试验结果表明，不同的冻融循环次数和初始含水率对小孔径孔隙（〈10 nm）之间的结构影响不大；冻融循环作用主要损伤了大孔径孔隙（0.01～100 μm）之间的结构，从而降低了改良粉土的强度。The freeze-thaw cycle tests are carried out under different compacted degrees and initial moisture contents to explore the mechanism and the influence of the long-term strength of improved silt under freeze-thaw cycle effect. And then, unconfined compressive strength tests after different freeze-thaw cycles are conducted. The influence law of the long-term strength of improved silt subjected to freeze-thaw cycle effect is discussed. It is found that the unconfined compressive strength decreases with the number of freeze-thaw cycles increasing. Finally, it reaches a stable stage after 6 freeze-thaw cycles. The higher initial moisture is, the more attenuation amplitude of the compressive strength is after the same number of the freeze-thaw cycles. In order to find out the influence law of the microscopic structure under the effect of freeze-thaw cycles, the microscopic tests of improved silt are carried out. And then the damage mechanism of the microscopic structure under the effect of freeze-thaw cycles is found out. It shows that different numbers of freeze-thaw cycles and initial moisture contents have less effect on the small pores （ 10 nm）. Freeze-thaw cycles have main influence on the large pores （0.01～100 μm） between the soil aggregates, so it makes the strength of improved silt decreased.

关 键 词：改良粉土 冻融循环 长期强度 孔隙分布 

分 类 号：TU111.25[建筑科学—建筑理论]